OK, so that's not much of a revelation. But it's certainly true -- more than 60 million websites worldwide run on the open-source publishing platform, which first launched in 2003. Additional anecdotal evidence of the WordPress phenomenon: Within minutes of posting a query over at HARO asking businesses and professionals to share their favorite plug-ins, my inbox was flooded with people eager to talk about how they're using the platform. And these weren't your navel-gazing personal blogs or family-photo sites, either. Rather, the responses poured in from designers, marketers, corporate blogs, SEO pros, retailers and other business users. Once thought of as "just" a blog publishing tool, WordPress has grown up in its first decade.

"WordPress started as just a blogging system, but has evolved to be used as a full content management system and so much more through the thousands of plug-ins, widgets and themes," WordPress says on the "About" section of its website.

Indeed, part of the platform's popularity derives from the ability to customize it to your particular site needs, often without much in the way of technical know-how. Sure, it doesn't hurt if you've got coding skills -- that's true of many open-source platforms -- but they're by no means necessary to add tools for social media integration, security, site performance and other purposes.

In fact, simplicity is often the foundation of the most popular plug-ins. "As many as we have tried in the past, it's typically the uber-simple but useful plug-ins that stick around long-term," said Katie Laird, PR and social media manager at the online retailer Blinds.com, which uses WordPress to publish its company blog. "Bells and whistles just don't cut it and stop getting used pretty quickly."

It's no small achievement, either, when a couple of free plug-ins help a business quantify the bottom-line impact of various blogging, social media or related activities -- an area where many organizations are still feeling their way around in the dark. That's the case for Scott Benson, senior SEO manager at Vocus, the online marketing firm behind HARO, PRWeb and other services. Benson uses Yoast's plug-ins for SEO and analytics in tandem to help prove the dollars-and-cents value of Vocus' blog activities.

"We put a lot of effort into our content marketing and we need to show it is working," he said. The ability to add a Google Analytics custom variable, for instance, enables him to track new and return blog visitors and identify the ones that later -- perhaps even much later -- become leads or convert to sales. Previously, the company was only capturing blog visitors that converted on their first visit, only a partial picture at best. "We're now showing how our blog attracts new visitors and converts them to sales after one or several return visits," Benson said.

No doubt, WordPress is used by all kinds of people for all kinds of sites. We focused here on the plug-ins that matter most to businesses, the kinds of apps and add-ons that can show up in the bottom line. Keep in mind, too, that there might be WordPress plug-ins for the other applications you already use, especially if they're well-known. "If you use MailChimp, Constant Contact or Salesforce, there are some awesome plug-ins for all of those," said Ker Communications founder Nick Ker. Those are just a handful of examples; if you rely heavily on other online apps, it's worth checking to see if they offer WordPress plug-ins or integrations, too.

Read on for some of the top plug-in picks from business-minded WordPress users.

It seems like Yoast offers a simpler solution for SEO beginners or those running their own sites for their own personal businesses, which is a good thing. One thing I have always liked about WordPress is its simplicity, and that carries over to most of its add-ons.

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